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Registered: ‎02-16-2018
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Powerbeam AC GEn2 PtP Issues

[ Edited ]

We have a pair of PB400AC at remote locations and we are experiencing dramatic drop offs in throughput with what appears to be excessive noise on both ends of the link.

 

http://prntscr.com/jv7bkm

 

Upon advice from UBNT on another problem I opted for what I refer to as an 'odd' channel spacing, based on the first number of the spacing.   The use of these frequencies should, in theory seperate it from anything else in the area.

 

No matter what frequency/channel the radios are set to, withing 1/2 hour, often less, we see the same problem arising.

 

There are other radios on the site, but none on the same bearing as this pair, and the closest is an PB400ISO, again with around 90 degrees difference in bearing.

 

We saw this for a short time on another link using PB500's but after a few frequency changes over a number of weeks it seemed to disappear.

 

The problems we are having on this link (13.21kilometres) are crippling this section of our network.   It feeds a number of smaller sites all with rather irate customers hanging off of them.   Signal strengths are well below what they ought to be over this distance.   Airlink calculations show it should be around -65.   Actual is -74 one end, -75 the other.

 

http://prntscr.com/jv7hrf

 

It has been suggested that the radio is seeing its own reflection ( or so to speak) and this could be the cause of the problem, however unless a flock of wandering sheep can cause reflection, then there is little else that should interfere.   The site is high on a hill, 10m above ground level with drops off quickly in the direction of the centre bearing.

 

The far end is 64 metres off the ground, high on the lift housing of a highrise building, again, with nothing in the beampath.   

 

Not only do I ask for assistance from the community here, but I'm sure my customers will be screaming for help.

 

Thanks

Ubiquiti Employee
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Re: Powerbeam AC GEn2 PtP Issues

In some cases we have seen a UI bug which will show the channel you are operating on as red. This does not impact radio performance, and is likely one of the problems here if your operating channel turns red every time regardless of the channel used.

If your actual powers don't match the prediction, I'd suggest either an alignment, obstruction or configuration issue. Are you using the maximum allowable transmit power for this link?
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Re: Powerbeam AC GEn2 PtP Issues

We were able to resolve this matter in the short term by running the link on the low frequencies.   We understand that this is not really permitted, and we understand that no doubt there will be comments from other users about the implications of this, and it is wrong etc etc etc.   Landing at this frequency was as a result of selecting 'AUTO' frequency, and my forgetting to selecting the avoidance of Indoor Frequencies.

 

At the lower frequencies the problem completely disappears.   Throughput is back where is should be and power levels can therefore be reduced to what would be EIRP on the high frequencies.   The lower frequencies also returned the signal level back to -61 which was achieved in the original installation with chains a db apart.   Higher frequencies the signal level was less than -73 and chains were often more than 8db apart.

 

We've since moved the frequency back to where it ought to be, to a clean channel, with a noise level of -101dbm.   Withing 10 minutes of being back at theis frequency the noise level was reporting -49 and the link speed down to a couple of Mbps.

 

With this additional information, does this tie in with your theory on the known bug ( or in Microsoft speak - Undocumented feature Icon Wink  )  you mentioned in your reply?

 

To try an alleviate the problem we even went to the extrekme of downgrading the firmware to what these dishes had at installation ( 8.0.x), thinking that the buig wasn't there then and was perhaps co-incidental that it appeared after upgrade.   It made no difference.

 

 

Ubiquiti Employee
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Re: Powerbeam AC GEn2 PtP Issues

No, as I mentioned in my previous post, the UI bug which shows a channel red when there is not a large amount of interference does not impact radio performance. It sounds like you just have actual interference, possibly self-interference.
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Re: Powerbeam AC GEn2 PtP Issues

Self-Interference. This would imply that the radio signal is reflecting off of something nearby. I have sheep and fresh air between the two radio sites. The former is 9 metres below the centre line of the dish, and the land falls away the further you get towards the other radio, and of the "B" side for want of a better term, just plain old fresh air.

If it is indeed self interference, how would this occur, and what can be done to alleviate it, bearing in mind what I have said above. As for external interference, according to Airview, we are the only radio in the area, unless of course the sheep have developed hacking skills Man Happy

Thanks for all the support so far. Its frustrating trying to resolve issues that have no apparent cause.

Looking forward to anything you can offer that might help.
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Registered: ‎04-14-2017
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Re: Powerbeam AC GEn2 PtP Issues

To be honest, I do not know at this point. If you are the only transmitter around and see this regardless of which channel you move to when it didn't appear before, it would appear to be self-generated; but from the physical setup you describe, I don't see how this would be occurring.
New Member
Posts: 1
Registered: ‎01-20-2019

Re: Powerbeam AC GEn2 PtP Issues

Hello Ubnt Support. I have the same problem of the PBE Gen2.. can i have a full configuration of a PTP PBE Gen2 thank you

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Re: Powerbeam AC GEn2 PtP Issues


@James-tiags wrote:

Hello Ubnt Support. I have the same problem of the PBE Gen2.. can i have a full configuration of a PTP PBE Gen2 thank you


If you haven't already, please see THIS link for help configuring a PTP link.

 

If you are still not having any luck, please share a screenshot of the Wireless tab from both.

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